Process of treating rayon cakes



Sept- 28, 1954 A. s. BROWN ET AL 2,690,375

PROCESS OF TREATING RAYON CKES Filed Dec. 16, 1949 WA JMD C9555 ATTORNEY Patented Sept. 28, 1954 PROCESS 0F TREATING RAYON CAKES Alfred S. Brown, Hamilton, and Tompkins W.

Terwilliger, New Hartford, N. Y., assignors to .Slrenandoa Rayon Corporation, Utica, N. Y., a

corporation of Delaware Application December 16, 1949, Serial No. 133,479

4 Claims.

This invention relates to a process for the liquid treatment of freshly spun `rayon cakes, and more particularly to a process step therein.

One of the objects of the invention is to provide a method for effecting `uniform and rapid liquid treatment of freshly spun cakes of rayon yarn or thread.

A further object of the invention is to provide a method for pre-wetting freshly spun cakes of on yarn or thread so that they will resist f .lage caused by mechanical action during sub sequent liquid treatment thereof.

in the production of rayon in iilamentary form by the pot spinning method the yarn is spun into pots to form hollow yarn packages known in the srt as cakes. After the cakes have been removed from the spinning pots they are allowed to stand or age for several hours before being subjected to treatment. The cakes, usually laced or Wrapped in fabric coverings, are then Washed to remove the acid and salts present therein and originating from the spin bath. During this aging the cakes tend to lose moisture even though the aging room is kept as close to 100% relative ifnidity as possible. As the cakes lose moisture, uently non-uniformly, they tend to contract ln the subsequent treatment of such cakes by any process in which treating liquid is caused to pass through the cakes by a pressure differential, it is diiiicult to provide an eiective liquid seal for a batch of cakes of non-uniform height. If an efiective seal is not provided, treating liquid escaping under high pressure may cause collapse of the cakes or even actually blow the cakes out of position in the apparatus.

Cakes which have lost some moisture are also more likely to be damaged mechanically during the liquid treatment, for example by so-called "Wash-downs, i. e., derangement of the thread on the insides of the cakes. Such wash-downs may be caused by too rapid flow of treating liquids into the cakes. As the cakes age, salts may crystallize from spin bath residues present in them, and the mechanical action of the downward motion oi the cake sealing surface may cause such salt crystals to abrade the yarn. The pref-setting, in accordance with this invention, pioents mechanical damage by the abrasive action or" salt crystals because the water or aqueous solution used for pre-wetting reclissolves the crystals. In addition the pre-wetting, i. e., saturation oi the cake Wrappers and outer layers of the cakes with Water or suitable aqueous solutions prevents Wash-downs, apparently because thoroughly wet wrappers cling to the cakes better than dry wrappers, thus holding the thread layers in place and thereby preventing displacement thereof in the yarn package.

in accordance with the present invention the green cakes of rayon o the like, i. e., Cakes still containing acid and salt, which have been aged for several hours and which usually have non-uniformly lost moisture, are pre-Wet, usually With water, or with a suitable aqueous solution to saturate the cake Wrappers and the surface thread layers of the caire, i. e., so as to saturate the cake only to the extent that Water, or an aqueous solution, applied under no pressure differential, quickly penetrate the same. rlhis pre- Wetting substantially restores any loss in height which the cakes may have suered and renders the cakes more resistant to mechanical damage. The pre-Wet cakes, thus substantially restored to uniform height can then be readily and elTectively sealed against the pressure of the treating liquid, when treated in groups or batches.

rfhe accompanying flow diagram illustrates the nature and the purpose of the piewetting step and its relation to the other steps involved in the after-treating of freshly spun cakes of viscose rayon with fluids under pressure.

The pre-wetting of the cake wrappers and outer portions of the cakes with water, Which in addition may contain a small amount of a suitable surface-active agent to facilitate the saturation oi the cake wrappers and the outer thread layers of the cakes, as well as the Washing Which is to follow, may be accomplished by dipping the cakes brieiiy in or by spraying or sprinkling the cakes with Water or a dilute solution of a surface-active agent preferably having a temperature below 60 C.

Although this saturation or pre-wetting of the cake Wrappers and outer thread layers of the cakes is not to be regarded as an actual washing step, it serves to facilitate the subsequent Washing because the cake wrappers are more pervious when completely Wet. rhis improved perviousness makes faster washing possible.

Although the use of plain water or water containing an innocuous surface-active agent is preferred in this process, it is of course to be understood that such media may be alkaline, acidic or saline, or contain other ingredients provided they are compatible With rayon in the green stage. Thus the surface-active agents, and the other ingredients referred to above, must be sufficiently soluble and stable under pre-wetting conditions, i. e., in the presence of chemicals normally occurring in green rayon yarn. Thus the innocuous surface active-agents may be anion-active, cation-active or ion-inactive. Examples of such surface-active agents are sulphonated and sulphated fatty acids, polymerized ethylene oxides and long chain derivatives thereof, alkyl pyridine compounds having more than 8 carbon atoms in the alkyl group, etc.

Modification of this process will be recognized readily by those skilled in the art, and it is intended to include all modifications covered by the appended claims.

What is claimed is:

1. In a process for the after-treatment of green unsupported rayon cakes produced by the pot spinning method which have shrunk in height during the aging period after spinning and which are to be subjected to the action of treating liquids under a pressure differential without deformation thereof, the step of uniformally prewetting the surface thread layers only of each of said cakes to a degree sufficient to restore said cakes to their original uniform height whereby a rm uniform seal may be maintained on each of said cakes during the application of a pressure differential between the inside and outside of said cakes for the passage of said treating liquids.

2. A process as claimed in claim 1 wherein the 4 pre-wetting step is carried out on the green cakes while said cakes are covered by individual fabric Wrappers.

3. .A process as claimed in claim 1 wherein said pre-wetting step is accomplished by means of water.

4. A process as claimed in claim 1 wherein said pre-wetting step is accomplished by means of a dilute aqueous solution of an innocuous surfaceactive agent.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,736,681 Topham Nov. 19, 1929 1,973,953 Gordon Sept. 18, 1934 2,042,529 Huttinger June 2, 1936 2,058,576 Dulken Oct. 27, 1936 2,091,725 White et al Aug. 31, 1937 2,130,791 Dunham Sept. 20, 1938 2,243,000 Brown May 20, 1941 2,647,038 Doud July 28, 1953 2,647,039 Millhiser July 28, 1953 FOREIGN PATENTS Number Country Date 478,219 Great Britain Jan. 14, 1938 

1. IN A PROCESS FOR THE AFTER-TREATMENT OF GREEN UNSUPPORTED RAYON CAKES PRODUCED BY THE POT SPINNING METHOD WHICH HAVE SHRUNK IN HEIGHT DURING THE AGING PERIOD AFTER SPINNING AND WHICH ARE TO BE SUBJECTED TO THE ACTION OF TREATING LIQUIDS UNDER A PRESSURE DIFFERENTIAL WITHOUT DEFORMATION THEREOF, THE STEP OF UNIFORMALLY PREWETTING THE SURFACE THREAD LAYERS ONLY OF EACH OF SAID CAKES TO A DEGREE SUFFICIENT TO RESTORE SAID CAKES TO THEIR ORIGINAL UNIFORM HEIGHT WHEREBY A FIRM UNIFORM SEAL MAY BE MAINTAINED ON EACH OF SAID CAKES DURING THE APPLICATION OF A PRESSURE DIFFERENTIAL BETWEEN THE INSIDE AND OUTSIDE OF SAID CAKES FOR THE PASSAGE OF SAID TREATING LIQUIDS. 